In the wood industry it is of great importance to obtain precise measurements of the mass flow rate, and in particular the dry mass flow rate, in the material to be processed, in order to achieve improved control of the process parameters. A precise knowledge of the dry mass flow rate in the material is of a central importance for the quality of the end product in many processes within the wood and pulp industry. For example, the optimal amount of chemicals to be added in the processes is dependent on the dry mass flow rate, and in order to control the processes adequately it is of great importance to correctly estimate the dry mass flow rate in the material.
Previously known methods to estimate the dry mass flow rate is based on cumbersome and tedious measurements made on samples of the biological material, and subsequent estimations based on an estimated mass flow rate etc. However, it would normally take a day or more until a correct measure value could be obtained, which delays the overall processing. It is therefore a need for a fast and reliable method to estimate the dry mass flow rate.
Similar needs exist in other industries handling biological material. For example, it would be advantageous to have a fast and reliable method for estimating the dry mass flow rate in the biological material in the bio energy field, in order to control the burning process more precisely, and improve its efficiency.
An automated procedure for estimating a wet mass flow is disclosed in U.S. Pat. No. 6,493,418. However, apart from being directed to determining a wet mass flow, which is less useable for the industry, the proposed method is relatively simple, and would seemingly provide a relatively low accuracy and reliability.
There is therefore a need for a fast and accurate method and apparatus for estimating the dry mass flow rate of a biological material, such as in wood, which can e.g. be used directly by people in field work operation, be used in automated processes, and the like.